Studies on the factors affecting the growth and hemolytic activity of Anabaena variabilis

Abstract

The hemolytic activity of the cell-free culture supernatant of Anabaena variabilis OL S1 was investigated using the hemolysis of rabbit erythrocytes as an assay. The culture medium of A. variabilis started to exhibit hemolytic activity at the late exponential growth phase, and maximized at the stationary phase. The hemolytic toxin is heat-stable and can be extracted in dichloromethane. The hemolytic activities under different temperature, light intensity and pH showed a high correlation with the cell densities (r = 0.965, 0.951, 0.865, respectively), and the optimum condition is 28~30°C, pH 7.5~8.0, light intensity 120 μmol photons m −2 s −1 . The addition of 10~20 μg mL −1 chloramphenicol, an inhibitor of protein synthesis, exhibited no marked suppression on the hemolytic activity. The supplement of 1~20 μg mL −1 glycerol increased the hemolytic activity significantly, suggesting that synthesis of hemolysin was dependent on carbohydrate and lipid metabolism. The spectrum of erythrocyte sensitivity to the hemolysin indicated that rabbit erythrocytes were more sensitive to the hemolysin than were rat and human erythrocytes. Goldfish and cat erythrocytes were, however, insensitive to the hemolytic toxin of A. variabilis.

Transformation of Thylakoid Membranes during Differentiation from Vegetative Cell into Heterocyst Visualized by Microscopic Spectral Imaging

“…growth of around 28°C to 30°C (Wang et al, 2007). Despite the temperature difference, the appearance of a transient minimum of microscopic absorption at 24 h (Fig.…”

Evidence for the production of a proteinaceous hemolytic exotoxin by wild-type strain of Synechocystis sp. PCC 6803 (Cyanobacteria)

“…At the stationary phase, the cultures with an OD 730 of 1.6~2.0 were harvested for hemolysin extraction as previously reported (Wang et al 2007). Briefly, the cultures were centrifuged at 9,000×g for 5 min, the supernatants were enclosed into a dialysis sac (12-14 kDa, Pierce, USA) after filtering through a GF/F filter (average pore size 0.45 μm, Whatman, UK), and then concentrated to less than 1/20 volume by placing the sac into polyethylene glycol 20000 at 4°C overnight.…”

“…The erythrocytes of rabbit or sheep were prepared as described previously (Wang et al 2007) and adjusted to a final concentration of 1% (v/v). Hemolytic activity was assayed by mixing 0.6 mL hemolysin crude extracts with equal volumes of erythrocyte solution, incubated in 37°C for 3 h, and then centrifuged at 2,000×g for 5 min.…”

“…In cyanobacteria, hemolysin has been found only in a few species, including a marine cyanobacterium belonging to the Oscillatoriaceae (Hashimoto et al 1976), Synechococcus sp. Miami BG11 6S (Mitsui et al 1988), Anabaena variabilis OL S1 (Wang et al 2007), and the GT strain of Synechocystis sp. PCC 6803 (Nagai et al 2001;Sakiyama et al 2006).…”

Studies on hemolysis of hemolysin produced by Synechocystis sp. PCC 6803

“…Hemolysin is produced by many pathogenic bacteria (Parker, 2003;Tilley and Saibil, 2006) and several cyanobacteria (Hashimoto et al, 1976;Mitsui et al, 1988;Wang et al, 2007;Sakiyama et al, 2006;Liu et al, 2008). Hemolysis mechanisms are not only closely related to the virulence in pathogenic bacteria, but may also be an indicator of the toxicity for cyanobacteria invading some types of fish (Mitsui et al, 1988).…”